I've prayed behind an Imam for years and know he says Takbeer late, near the next pillar. Once, I got up a bit slower than usual from the first sujud but made it up before he said Allahu Akbar.But since he says it late, most likely he must've moved already from sitting position. Is my Salah valid?

Ustadh AbdulAziz al-Haqqan

This seems to be waswas.